Creating Tshirt Product Error

Hi, I’m getting the following error when I try to create a product on the Streetshirts website. Can anyone let me know how to resolve this, bearing in mind I’m not very technical, Thanks…

Server Error in ‘/’ Application.
{“code”:”woocommerce_rest_cannot_create”,”message”:”Sorry, you are not allowed to create resources.”,”data”:{“status”:401}}
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Exception: {“code”:”woocommerce_rest_cannot_create”,”message”:”Sorry, you are not allowed to create resources.”,”data”:{“status”:401}}

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[Exception: {“code”:”woocommerce_rest_cannot_create”,”message”:”Sorry, you are not allowed to create resources.”,”data”:{“status”:401}}]
WooCommerceNET.<SendHttpClientRequest>d__19`1.MoveNext() +2560
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +31
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
WooCommerceNET.WooCommerce.v1.<PostProduct>d__38.MoveNext() +324
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +31
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
Streetshirts_Connect.ext.woo.<btnAddProduct_Click>d__10.MoveNext() +5338
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +31
System.Web.Util.SynchronizationHelper.SafeWrapCallback(Action action) +106
System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +31
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
System.Web.Util.WithinCancellableCallbackTaskAwaiter.GetResult() +32
System.Web.UI.<ProcessRequestMainAsync>d__523.MoveNext() +8699

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.7.2053.0